I remember now . I was installing netbsd unix
on an old mac computer and I started
reading about unix.

Here's the reference

Visual Quickstart Guide
Unix Third Edition

by Deborah S. Ray and Eric J. Ray

Code:

If you use && to combine commands,
the system will run both in sequence but
run the second only if the first succeeds.
For example, you could use

mv todolist todolist.done && touch todolist

to move your to-do list to a different file and
create a new to-do list. If the first command
fails (for example, because you don't have
permission to create a new file), the second
command won't run.

Aha! That's a valid reason to have such a command, in addition to ";" (which runs regardless)

I learned something new today! Thanks Don!

Quote:

With Puppy linux there isn't many permissions issues,
so nobody uses the double ampersand.
Now I understand the confusion.

Well, most people don't even use the command line any more, so...

I guess that I was aware that "&&" also worked, but because "&" is a "special character", I avoided it. From the error standpoint, I find that ";" is more well behaved -- and when it doesn't work, it doesn't do exceptionally strange things -- like backgrounding jobs...

BTW, it rather looked like part of the problem was that characters we being "quoted" rather than being operators...

There's that whole goofy list of special characters, such as: "&" versus "\&" and what's the really goofy one..."\\\" which quotes "\" as a character (I _think_)? ("\" being the special character used for quoting, is difficult to "quote", so you have to "quote" it again...or is it twice more?)